The present invention generally relates to surgical instruments and methods for use of the same, and more particularly, but not exclusively, relates to instruments and methods for stabilizing bony structures.
The use of various devices and methods for stabilizing bone structures have been used for many years. For example, the fracture of an elongated bone, such as a femur or humerus, can be stabilized by securing a plate to the fractured bone across the fracture. The plate extends across the fractured area and thus stabilizes the fractured components of the bones relative to one another in a desired position. When the fracture heals, the plate can be removed or left in place, depending on the type of plate that is used.
Another type of stabilization technique uses one or more elongated rods extending between components of a bony structure and secured to the bony structure to stabilize the components relative to one another. The components of the bony structure are exposed and one or more bone engaging fasteners are placed into each component. The elongated rod is then secured to the bone engaging fasteners in order to stabilize the components of the bony structure.
One problem associated with the above described stabilization structures is that the skin and tissue surrounding the surgical site must be cut, removed, and/or repositioned in order for the surgeon to access the location where the stabilization device is to be installed. This repositioning of tissue causes trauma, damage, and scarring to the tissue. There are also risks that the tissue will become infected and that a long recovery time will be required after surgery for the tissue to heal.
Minimally invasive surgical techniques are particularly desirable in, for example, spinal and neurosurgical applications because of the need for access to locations deep within the body and the danger of damage to vital intervening tissues. The development of percutaneous minimally invasive spinal procedures has yielded a major improvement in reducing recovery time and post-operative pain because they require minimal, if any, muscle dissection and can be performed under local anesthesia. These benefits of minimally invasive techniques have also found application in surgeries for other locations in the body where it is desirable to minimize tissue disruption.
Examples of instruments and techniques for performing surgeries using minimally invasive techniques are found in U.S. Pat. Nos. 5,792,044 and 5,902,231 to Foley et al. While these techniques are steps in the right direction, there remains a need for instruments and methods for stabilizing bony structures using minimally invasive techniques. This need and others are addressed by the present invention.
The present invention relates to devices and methods for insertion of an orthopedic brace to one or more anchors secured to an animal subject.
In one aspect of the invention, there is provided a method for using an instrument to connect at least two bone anchors with a connecting element. The instrument is secured to the anchors and manipulated to place the connecting element in a position more proximate the anchors.
In another aspect of the present invention, there is provided a method that includes: placing at least two anchors in a bony structure, each of the anchors having an extension associated therewith; attaching a brace inserter of an installation instrument to the extensions; and guiding a brace into a desired position relative to the anchors.
In a further aspect of the invention, there is provided an instrument for placing a brace or connecting element into a desired position relative to at least two anchors. The instrument employs a fixed geometric relationship to guide the connecting element into a position proximate the anchors.
In yet a further aspect of the invention, there is provided an instrument for placing a connecting element into a desired position proximate the location of two anchors. The instrument is mounted to the at least two anchors and holds the connecting element in spatial relation to the anchors about a pivot point. The instrument is rotated about the pivot point to guide the connecting element to the desired position.
According to an additional aspect of the invention, there is provided an installation instrument having a brace secured thereto. The brace is indexed so that the brace can assume only a desired orientation when secured to the installation instrument.
According to one aspect of the invention, the percutaneous brace placement device includes first and second anchor extensions and a pivoting brace inserter mounted to the anchor extensions about a pivot axis. The pivoting brace inserter includes an arm having a brace mounting portion at its distal end for connecting an orthopedic brace to the device.
In another aspect of the present invention, the installation instrument includes a support arm engaged to the anchor extension. An anchor is engaged to the distal end of each anchor extension. Preferably, the anchors are in the form of a multi-axial screw capable of allowing universal rotation of the anchor extension. In one form, the arm is located at a predetermined radius from the pivot axis and in a curve at a substantially constant radius relative to the pivot axis to the brace mounting portion. In yet another form, a brace gripper or coupler is operable to selectively grip and release an orthopedic brace from the inserter. In another form, a brace has one end connected at the brace mounting portion and an opposite end adapted to puncture soft tissue of an animal body. Preferably, the brace and pivot arm lie in a circle centered on the pivot axis at a constant radius. The brace is curved at the constant radius relative to the pivot axis in one plane, and the brace is oriented to lie in the circle.
According to another aspect of the invention, a method of installing an orthopedic brace in an animal subject is provided. The method comprises placing first and second anchors mounted on first and second anchor extensions, respectively, percutaneously in first and second bony parts of the body of the subject; mounting a brace inserter on the anchor extensions, the inserter having a pivot axis about the anchor extensions; mounting the brace on the pivoting brace inserter; and swinging the brace inserter relative to the anchor extensions about the pivot axis and thereby moving the brace in a forward direction through an arc centered on the pivot axis and introducing an end of the brace percutaneously to the location of the anchors. In a further form, the brace is fixed to the anchors; the inserter disconnected from the brace; and the inserter moved in a reverse direction through the arc and to remove the inserter from the body. Preferably, the brace is a shaft curved at a single radius about an axis co-linear with the pivot axis of the arc, and the method further includes introducing the shaft through receivers in the anchors during the introduction step.
In yet another aspect of the present invention, anchors, or anchors and anchor extensions are placed by image guided navigation to locate optimum placement and orientation of the anchors in pedicles of vertebral bodies of a single level of the spine of the animal. The image guided technology is also used to determine animal skin locations for percutaneous puncture entry of the anchors. In one form the anchors are cannulated and inserted over guidewires anchored in the vertebral bodies.
According to another aspect of the invention, a technique for spinal fusion of adjacent vertebral bodies of the animal spine is provided. The method includes removal of intervertebral disc material from the space between first and second vertebral bodies of the subject. One or more interbody fusion devices are introduced into the space. First and second anchors are engaged to the first and second vertebral bodies, respectively, through first and second percutaneous punctures in the subject. A curved brace is installed through a third percutaneous puncture in the subject using an installation instrument. The brace is connected to the anchors by application of fastening tool to the anchors through the first and second punctures.
In another form of the present invention, a curved brace is installed by swinging the brace through an arc in a plane containing the brace and perpendicular to the axis of curvature of the brace, and passing portions of the brace into passageways in the anchors. The pivot axis of the brace is at a fixed distance from the passageways equal to the radius of curvature of the brace.
One object of the present invention of the present invention is to provide minimally invasive techniques and instruments for stabilizing a bony structure in an animal subject.
Related features, aspects, embodiments, objects and advantages of the present invention will be apparent from the following description.